Help Wiring Squirrel Cage fan

[Luscombe1940]

Hi Everyone,

I was able to salvage a good squirrel cage fan from my son-in-laws furnace when they replaced their HVAC system. I have a large garage with a high ceiling and a modine heater in it. Plan on moving some air in the cold months to keep the floor level warmer.

I am handy with wiring but this one is over my head. There are several different color wires, red, white, yellow, blue, black. The motor is 110v and I think it has condensers on the side (brown wires). Can someone guide me in how to wire this to a switch. I would settle for a single speed but multi switch/multi speed would be ok too.

Thanks,
Gary

 

[48RON54]

you should pull the motor and look at the tag on the side. Its going to tell you what each wire is for. There has to be a way to get at least 2 speeds working, but I have no clue how complicated that would be to figure out.

I just had to replace my blower motor and the supposed factory OEM part was not even close. It was quite the learning lesson on motors. There are also tons of videos on youtube on testing motors. Those are really helpful to help familiarize yourself with the motor. They made me more comfortable tackling that project anyway.

 

[48RON54]

I'm subscribed. I'm interested to find out how to do this.

 

[naturalgas]

Black or yellow may be the highest speed.So white common , yellow of black hot. Wire a cheater cord and try each one to get speed you want. Two Browns are for capacitor.


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[naturalgas]

I can see the capacitor in pic brown wires attach to that. Keep in mind that you will need some resistance in front of that blower or you will blow that motor out real quick. Hold a piece of cardboard in front of blower when you plug it in then remove it you will see what I mean.ok here it is. black is high speed. Blue medium high, yellow medium low and red low speed


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[Luscombe1940]

I can see the capacitor in pic brown wires attach to that. Keep in mind that you will need some resistance in front of that blower or you will blow that motor out real quick. Hold a piece of cardboard in front of blower when you plug it in then remove it you will see what I mean.ok here it is. black is high speed. Blue medium high, yellow medium low and red low speed


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Thank you for the response.
Couple questions for you.

I was hoping to use this motor without any duct work as a way to move air in the garage, as in suspend it above the floor from the ceiling and let er blow. Do I understand that once the motor is started with a resistance, that it will run fine unrestricted or is the lack of back pressure going to cause it to over rev?

I suppose I could fab a neck of duct on the discharge side to create some resistance.
Short of that, I would build a wood box, set the fan in and then use a guillotine type gate in front of the fan.

 

[naturalgas]

You will need some type of resistance . You will have to secure it somehow anyway. Maybe build a box for it and fashion it to hold an air filter.


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[Elginz]

A pic of mine, White to White, line to the speed desired, black, blue ,or red in my case, I believe the black is low. It does say on the fan motor.

 

[nehog]

You will need some type of resistance . You will have to secure it somehow anyway. Maybe build a box for it and fashion it to hold an air filter.

Is there any documentation for the need to have some resistance?

 

[Rick M]

Put something on the **** side for resistance, not the output. You want to slow the fan so it doesn't overheat.

-- Rick M

 

[TractorJeff]

Again, Is there any documentation on this "air resistance" thing?
If it was Free, I would wire it and run it, if it died, Well? Lesson learned. What little I know about fans, the size of the blower dictates the resistance. That motor is NOT a universal type hence it will/should run at Synchronous speed.

 

[marinusdees]

If you run it without resistance, the motor will overheat due to overloading and the thermal overload protector will open, stopping the motor until it cools. This is counterintuitive in that the more resistance to airflow you have, the less the motor works. If these intermittent stops don't affect your intended purpose, no problem. If you want continuous running, the way to figure airflow resistance is to use a clamp on ammeter and add resistance until the current consumption is no higher than nameplate rating. If you don't believe this, use a clamp-on ammeter and try it. Oh, and good luck.
The more air it moves, the harder the motor works. Think about how your vacuum runs faster when you restrict airflow, because the motor is working LESS.

 

[nehog]

If you run it without resistance, the motor will overheat due to overloading and the thermal overload protector will open, stopping the motor until it cools. This is counterintuitive in that the more resistance to airflow you have, the less the motor works. If these intermittent stops don't affect your intended purpose, no problem. If you want continuous running, the way to figure airflow resistance is to use a clamp on ammeter and add resistance until the current consumption is no higher than nameplate rating. If you don't believe this, use a clamp-on ammeter and try it. Oh, and good luck.
The more air it moves, the harder the motor works. Think about how your vacuum runs faster when you restrict airflow, because the motor is working LESS.

Unless the blower was incredibly badly designed, the idea that running the blower no-load causing an overload is meaningless.

Your comparison to a vacuum cleaner with an obstructed intake is also meaningless. Obstruct the vacuum's outlet and see what the results are!

Again cite verifiable references for this.

 

[Rick M]

I never allowed one to overheat until it shut down but they get extremely hot if run without resistance, too hot to hold your hand on it. I don't bother with ammeters, I just cover a portion of the inlet and feel the motor temp, when it settles to just slightly above room temp I stop. There are several ways to provide resistance. Most common is by using air filters. Barring that you can close off a portion of the inlet by blocking a portion with cardboard or whatever; or a piece of pegboard works nicely.

I respect skepticism but have no reference other than experience. Take it or leave it.

 

[Dustball]

Unless the blower was incredibly badly designed, the idea that running the blower no-load causing an overload is meaningless.

Your comparison to a vacuum cleaner with an obstructed intake is also meaningless. Obstruct the vacuum's outlet and see what the results are!

Again cite verifiable references for this.

http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html

Centrifugal fans move air by throwing the air outwards through centrifugal force. The amount of air the fan is moving decreases as the resistance to airflow increases. If the fan blades are moving less air, they can actually spin easier because there is less air to sling. This causes the motor RPM to increase and the motor amp draw to decrease.

Actual testing-
http://cr4.globalspec.com/comment/427149/Re-Blocking-off-inlet-on-squirrel-cage-blower

 

[marinusdees]

Thanks for this. Seems like this is what I said, or, meant.

 

[marinusdees]

Unless the blower was incredibly badly designed, the idea that running the blower no-load causing an overload is meaningless.

Your comparison to a vacuum cleaner with an obstructed intake is also meaningless. Obstruct the vacuum's outlet and see what the results are!

Again cite verifiable references for this.

Seems you got your verifiable references.

 

[naturalgas]

I also have no reference except 36 years of replacing bad motors. I do know you need some resistance for a long happy motor life.


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[marinusdees]

I also have no reference except 36 years of replacing bad motors. I do know you need some resistance for a long happy motor life.


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Amen.

 

[nehog]

Seems you got your verifiable references.

I'm not sure that meets the verifiable part, but I'll drop the issue since everyone seems to think I'm wrong.

I'll just leave this:

1. A properly designed system will not fail or operate adversely when operated no load, low load, or full load. That is what engineering is for--to make sure the device works properly under all operating conditions.

2. Blocking or otherwise restricting the output of a blower would not serve to reduce the load on the motor. That's simple physics and engineering.

3. If restricting the input of a blower was necessary to the devices safe operation, then said restriction would have been built in at the factory. Not something that every user would have to account for (at a hit-or-miss basis in fact.)

 

[Elginz]

If air is like water, and it is, we had to throttle back water pumps (7-10 hp range) with a valve to the amp rating on the motor. I don't think this is a problem with furnace blower. The manufacture can not tell if every blower is going to have a plugged filter, a plugged heat exchanger or any filter at all. I believe a plugged filter is most damaging. Like what is said above.




"1. A properly designed system will not fail or operate adversely when operated no load, low load, or full load. That is what engineering is for--to make sure the device works properly under all operating conditions.

2. Blocking or otherwise restricting the output of a blower would not serve to reduce the load on the motor. That's simple physics and engineering.

3. If restricting the input of a blower was necessary to the devices safe operation, then said restriction would have been built in at the factory. Not something that every user would have to account for (at a hit-or-miss basis in fact.)"

 

[Rick M]

1. A properly designed system will not fail or operate adversely when operated no load, low load, or full load. That is what engineering is for--to make sure the device works properly under all operating conditions.

"No load" is not a normal operating condition and would not be part of the system.

More reading:

http://www.motorsanddrives.com/cowern/motorterms8.html

motor load actually decreases as the output or input to the blower or pump is blocked off or restricted. This would be the situation in Figure 1 as the valve is closed. The reverse of this is that motor load increases dramatically as restrictions are removed.

 

[Brian_WK]

All centrifugal blowers have resistance on them whether it be a filter, heat exchanger, Evap coil or duct work (static pressure). If the motor is not allowed to spin at its proper operating speed it will continue to pull higher amps due to its inductive load. If you don't want to have a air flow restriction you can do through figure out how many blades are on the squirrel cage and remove a common denominator amount from it and then re-balance the cage. Or another possibility is to put in a larger motor (might not fit) or a smaller squirrel cage that is rated for lower CFM per RPM. Or save the hassle just add a restriction to the flow of air.

Brian

 

[marinusdees]

I'm not sure that meets the verifiable part, but I'll drop the issue since everyone seems to think I'm wrong.

I'll just leave this:

1. A properly designed system will not fail or operate adversely when operated no load, low load, or full load. That is what engineering is for--to make sure the device works properly under all operating conditions.

2. Blocking or otherwise restricting the output of a blower would not serve to reduce the load on the motor. That's simple physics and engineering.

3. If restricting the input of a blower was necessary to the devices safe operation, then said restriction would have been built in at the factory. Not something that every user would have to account for (at a hit-or-miss basis in fact.)

This is dropping the issue??

 

[Elginz]

Once and for all. Motor rated 6 amps. free flow it is almost 9 amps, one side covered, 6 amps and blows a lot more air. Had the same result on my other blower.

 

[Elginz]

By the way this also holds true for the exhaust side. As I closed off the opening the amps went down.

 

[marinusdees]

Once and for all. Motor rated 6 amps. free flow it is almost 9 amps, one side covered, 6 amps and blows a lot more air. Had the same result on my other blower.

Surprise!!

 

[LS6 Tommy]

Wht =Neutral
Blk = High
Blu = Medium
Red =Low
Yel = Medium Low on 120V OR L2 on 230V

Brn = run cap.
Brn/Wht stripe = run cap.

There's a lot of false info here. As previously stated (and proven) restricting a squirrel cage blower outlet does not overload it. It is not a positive displacement pump. Restricting the inlet or outlet both reduces load, but too much reduction in airlfow technically could cause overheating from lack of motor cooling, but it's not very common. Resticting inlet or outlet also allows the blower to overspeed and on large blowers this can allow the rpm to go above the maximim rating for the blower wheel and it may come apart. Squirrel cage blowers are designed to run with positve static pressure in the ductwork and running them completely open can and will cause them to overload the motor. In other words, some "restriction" IS necessary and it's almost always done on the outlet. There are vane dampers on the inlets of large industrial blowers that are used for air volume control, but they are not used to adjust the load on the motor. Usually these days the vane dampers are mechanically locked full open and a VFD is used to control air volume by reducing motor speed.

If you want to use one as a free standing blower for air circulation, experiment with partilaly blocking the lower part of the outlet (the area closest to the blower center, where is a little "baffle" inside) with the motor on "high" until you get fairly close to the amperage rating of the motor

Tommy

 

[marinusdees]

Wht =Neutral
Blk = High
Blu = Medium
Red =Low
Yel = Medium Low on 120V OR L2 on 230V

Brn = run cap.
Brn/Wht stripe = run cap.

Thers a lot of false info here. Restricting a squirrel cage blower outlet does not overload it. It is not a positive displacement pump. Restricting the inlet or outlet too much may cause overheating from lack of motor cooling. Resticting inlet or outlet also removes the load from the motor and on large blowers this can allow the rpm to go above the maximim rating for the blower wheel and it may come apart. Squirrel cage blowers are designe to run with positve static pressure in the ductwork and running them completely open can cause them to overload the motor. Inother words, some "restriction" IS necessary.

Tommy

There is a lot of false information here. No doubt. Also a fair mount of misspelling and incorrect grammar. Oh, well. Keeps us awake.

 

[LS6 Tommy]

There is a lot of false information here. No doubt. Also a fair mount of misspelling and incorrect grammar. Oh, well. Keeps us awake.

I think I got all my spelling and grammar errors ironed out on my edit...

Tommy

 

[marinusdees]

I think I got all my spelling and grammar errors ironed out on my edit...

Tommy

Resticting is not in my lexicon. Sorry.